Body boards for riding waves and other recreational sports boards made of foam or other floatation material are known in the prior art. In general, such sports boards are composed of a number of layers thermally or adhesively bonded together. The boards generally have a closed-cell foam core covered by one or more layers adhesively or thermally bonded to the core.
A number of laminated boards are known in the prior art and a number of methods of laminating or bonding the various layers of the board together are known. Examples of such boards and methods of laminating them are shown and disclosed in U.S. Pat. Nos. 5,211,593, 5,658,179, 5,503,921, 4,850,913 and 5,275,860. In bonding the layers together it is desirable to provide a bond between two layers which is stronger than the strength of the layers themselves.
It is known in the prior art that an adhesive may be used to bond the various layers together. This method of bonding has a number of drawbacks, including the adverse affect of solvent vapors released into the air during the manufacturing process and the added weight to the board of an adhesive joint. In addition, many conventional adhesives eventually deteriorate over time from the adverse affect of salt water on the adhesive, causing delamination.
It is also known that heat may be used to bond the various layers together. However, boards known in the prior art generally require that the thermal laminating process by which they are made occur at very high and exact temperatures in order to properly bond the layers. The requirement for a high and exact bonding temperature necessitates a more elaborate laminating process and can cause undesirable shrinkage of the layers. This type of bonding is especially difficult when the layers are of different materials having different thermal characteristics.
For example, it is known that polyethylene foam sports boards can be covered with an outer skin surface of non-foam plastic materials for drag reduction or for applying a printed graphics to decorate the sports board. Various techniques are known in the prior art to laminate such a slick plastic film to the foam core of the board. For example, U.S. Pat. No. 4,850,913 teaches the process of heat laminating a polyethylene film to a thin polyethylene foam sheet, and then heat laminating the resulting film-foam laminant to a low-density polyethylene foam core. This intermediate foam sheet is sometimes referred to as a backing foam layer. Similar, U.S. Pat. No. 5,658,179 teaches a body board having a slick polymer film applied to the bottom of the board and having an outer high density core laminated to a lower density inner foam core. However, these fabrication techniques require including a high density foam sheet (backing foam) between the outer film layer and the foam core to improve and provide proper bonding between the film and low density foam core.
Some manufacturers have attempted to heat laminate a plastic film directly to a foam core without a backing layer of high density foam between the outer film layer and the foam core. An example of this is shown in U.S. Pat. No. 5,211,593. The board shown in U.S. Pat. No. 5,211,593 includes a graphic imprinted dual film layer heat laminated to a foam core by pressing the film layer against the foam core surface after the foam core surface has been heated to a desired temperature range. Another example of this direct lamination technique is disclosed in U.S. Patent Publication No. 2002/0167136. However, such direct lamination techniques require high and exact temperature ranges to achieve proper fusion bonding between the outer film layer and the inner foam core. The intense heat involved in such a neat lamination process also may cause undesirable shrinkage of the film layer, particularly with thin gauge polymer films. The heating process may also cause unnecessary melting of the foam surface layer, which may result in a rough finish on the film surface or blistering at the interface between the foam layer and the film layer. In addition, boards without an intermediate foam layer often do not have the desired comfort or softness on top of the board, do not absorb collision forces effectively, and do not provide adequate flexural strength.
Accordingly, there is a need for a sports board that can be manufactured cost effectively, has a comfortable riding surface, and includes a sharp and distinct graphic imprinted outer film layer, a slick plastic bottom skin with good surface smoothness, good bonding between the layers, and protection against impact forces.